My boyfriends birth son

Im trying to find my boyfriends son. Hes adopted name is Eric Criag Heck. Hes just turn 16. He was born on Sept 10 1990. Hes last birth name is Maier. Well, My boyfriends ex gave all the 4 kids up for a man when they was at the age 11 and 6. Two of the kids is his. He tried to get his step kids but they wont let him because the birth fathers wont sign thier rights. So, My boyfriend put the kids in his exs dads home because he runs a foster home and my bfs exs dad adopted all of them. Now, My bfs 2 step kids and his daughter is in the same town as we are. His step daughter live across the street from us and she has 2 kids. His daughter come by and call almost eveyday. Anyways, 2 years ago Eric ranaway from his grandmas because his grandmas wife beat him. His grandmas is in a old folks home becuase his wife put him there. So, The foster care moved him from the home. When he went to another foster care his mom and his sister follow the lady to find out where he is. A Year ago the lady wanted to adopted Eric but he dont want to change his last name. I know his old enough to make up his mind but I think his family had alot to do with it. They put stuff in his head. Eric is kinda slow. So, He dont know what to think everyone is telling him what to do. Well, A couple of months ago The lady just gave him up and not telling his family where he is. She probably dont know where he is. She must had a reason to do that. Maybe because his mom put stuff in his head. I dont blame her. He needs to think on his own. Plus His mother is not allowed around him until hes 18. My bf and I dont talk to him but I did wrote him a couple of times. So, I know its not us doing harm. Hes 16 and he knows where his moms is. He will find her when hes 18. We lived like 3 blocks away from his mother. He knows he has a brother but I dont know he knows he has a new baby sister. I sent pictures not to long ago and I didnt got it back. So, He probably got the letter.